The present invention relates to gas generators used to inflate air bags in an automobile occupant protection system and, more particularly, to a head curtain inflator designed to protect the occupants of a vehicle during a rollover accident. The novel design provides a steady and uniform production of gas thereby providing sustained inflation of the airbag across its length, and is particularly useful as a linear head side airbag inflator.
Inflation systems for deploying an air bag in a motor vehicle generally employ a gas generator in fluid communication with an uninflated air bag. The gas generator is typically triggered by a firing circuit when the sensed vehicle acceleration exceeds a predetermined threshold value, as through the use of an acceleration-responsive inertial switch.
Air bag inflation systems designed for rollover accidents often utilize a gas generator stored within the B-pillar of the car, for example. Hybrid gas generators are typical and contain pressurized gas that is released upon receipt of a predetermined signal. The gas must then be transferred to the point of application and thus requires additional plumbing.
Certain known side-impact inflators require plumbing to convey gas generated in a relatively remote gas generator to the airbag, thus complicating the manufacturing of the vehicle occupant protection system and furthermore resulting in a relative delay prior to airbag inflation.
Other known gas generators sometimes result in less than optimum inflation profiles. For example, original equipment manufacturers oftentimes require sustained inflation of the airbag thereby ensuring continued protection during a rollover accident. To ensure sustained inflation, gas generant compositions must exhibit sustained combustion over the desired or required time.
Gas quantities plumbed to the airbag are often not uniform across the inflation profile of the airbag. Stated another way, a portion of the airbag may inflate or pressurize to a greater degree than another portion of the airbag. As a result, the airbag may provide less protection in the regions not completely inflated.
As such, a challenge remains to provide sustained and uniform inflation across the length of airbag employed for vehicular side-impact protection.
Related vehicle occupant protection systems are known. U.S. Pat. Nos. 5,322,322, 5,094,475, 3,733,088, 5,540,459, 5,588,672, and 5,921,576 are cited by way of example and are herein incorporated by reference.
The above-referenced concerns are resolved by a vehicle occupant protection system of the present invention. In accordance with the present invention, a side-impact head curtain inflator contains an elongated housing. Gas exit apertures are spaced along the length of the housing thereby facilitating the release of gas. A propellant body is contained within the housing and is substantially coextensive therewith. An ignition body or rapid deflagration cord is juxtaposed or contained within the propellant body and is substantially coextensive and in physical contact therewith. An airbag or side-impact head curtain airbag extends along the length of the housing and is in fluid communication therewith.
In a preferred embodiment, the propellant body contains a mixture of silicone as a fuel and an oxidizer. The pliant nature of silicone promotes the extrusion of a long cylindrical body coextensive with the housing. The ignition body may be contained within the cylindrical body of the propellant, axially disposed for example.
Silicone employed as a fuel results in a sustained burn and therefore sustained combustion. The ignition body or rapid deflagration cord provides an essentially simultaneous ignition and burn across the length of the propellant. As a result, gas exiting the gas exit orifices spaced along the length of the housing uniformly inflates an airbag sealed about the length of the housing and in fluid communication therewith. In operation, once a crash event occurs, the airbag is immediately deployed exhibiting a sustained and uniform inflation profile across the length of the housing.